Grievance against bully and also management. Advice appreciated, Thanks in advance

I had a good friend on the telephone last night in tears, her daughter Jane is being bullied at work.This has been going on for the best part of two years. Some how for most of the time she has managed to cope and with the support of few good friends where she works has kept her chin up. The person that is her main bully is her supervisor, lies have been spread about Jane and there has been other lesser incidents with other employees.She has made the manager aware on several occasions verbally of the the bullying but never in writing. She has been told by the manager to shrug it of, rise above, laugh it off. Other times her manager has said that the bully is stressed and vulnerable. Or even its just her way, ignore it, don't take it personally
A few weeks ago everything came to a head. Due to a training course ,Jane is being forced to worked more closely with the bully. (This training course will eventually make her above the bully). On occasions the bully has been uncooperative and un-agreeable generally making things difficult. Again this was pointed out to management and eventually the bully worked along side in relative harmony, light at the end of the tunnel shall we say.
They worked on a training schedule, in order to train other employees. Then on the agreed date, they set about training the other staff, at first all went well, then the bully changed the agreed schedule and things got out of control. My friends daughter pointed out that they needed to to get things back on track. To which the bully threw a wobbly, hurling abuse and then leaving the session. The deputy manager went after her spoke to her and returned to the session and told Jane that she needed to go and speak to the bully and sort things out. On attempting to speak , more abuse was directed at Jane. Unfortunately instead of walking away from the situation, she finally stuck up for herself. Unfortunately there were no witnesses.Then her second mistake, she went to the deputy manager in angry mood she tackled her about putting her in a situation with the bully, when she was aware , there was an ongoing problem. Jane shortly after apologised for speaking out order. She has since been told she should have had a disciplinary over it.
The bully also spoke to management and turned things around by lying and they wont believe Jane versions side of the story and as always Management stuck up for the bully.
After this event Jane was signed of with Stress and after over three weeks illness returned to work( approx. two weeks ago.)
While Jane was ill,a volunteer sent ( the place of work is a charity) a complaint to Head Office,with concerns about the bully and how unhappy many of the staff were. It turns out that the volunteer and several others had been at the receiving end of the bully's tongue.
This started a investigation by the area manager, and all staff were interviewed, they were told confidence . So they were very open with their answers.
Jane was informed by one or two friends they had been interviewed, at first she was relieved, then she was filled with dread that she would be blamed for the volunteers actions. As she felt she could no longer approach management
she wrote to the area manager a very lengthy letter, explaining the reasons why she was ill and also pointed out that she felt she could no longer approach her Manager ..
Since her return to work, management have been very off with her and snappy.Yesterday the area manager, along with her manager had her in the office, basically, they believe that there has been a conspiracy to discredit the bully, and that the letter and interviewed employees claims are unfounded. The bully has now put in a formal complaint against Jane, stating that it she has been bullied by Jane, Jane feels that management will support the bully.
Four others employees have now been threatened with disciplinary and invited to leave. Jane is now considering Grievance against Bully and also the Manager.
Advice please

Thanks for quick response mccluff. Jane apparently doesn't know whether or not she is now in a disciplinary or not she cant recall if they stated she was. She was a bit shell shocked according to her Mum.Her manager was in the meeting noting down everything that Jane said, which Jane felt intimidated by. She had pointed out to her Area Manager in her letter that she wasn't confident about her manager and couldn't approach her any more. Should the manager even have been in the meeting?

Mccfluff I have just spoken to Janes Mum, apparently they are bringing in an external person and will be questioning both Jane and Bully next week. It will his/her decision who is the bully. Whichever one will be dismissed. If Jane's management had been more proactive with Janes complaints instead of dumbing down. Jane would not be in this situation.

redhelen, she has no documentation, but she can remember lots and approx dates they happened, she always followed her Managers advice, which she trusted. I believe she will be documenting over the weekend.
I have now been informed that some of the other 4 employees who are being accused of conspiracy are thinking about grievance against management. They also have made complaints about the bully in the past , and received the same attitude from the Manager. They gave up complaining completely. Do you think they have a case against the manager ?

Mccfluff, thanks will pass this on. As notes were being taken by her manager, do you think this was a disciplinary meeting ? and due to the fact that she had explained to the area manager her lack of confidence in her manager, which the manager is now aware off. Should the manager even have been in the room. She wasn't asked if she needed a workmate as witness. All she was told about the meeting was that the Area Manager was going to chat to her about her letter to him. No discussion about her letter was made apparently, the letter and supposed conspiracy was and the fact that she had a complaint that she was bullying her supervisor.

EDDIE Would that not look like its a conspiracy, they have already been accused of that.
The letter wasn't sent by an employee , but by a volunteer who works there a few days a week. The employees were interviewed in what was meant to be confidential interview and gave honest and open answers to see if there was any justification to the Complaint by the volunteer.. Yet they are now being threatened with disciplinary and invited to hand in the notices from the findings of what was meant to be confidential. Doesn't sound right to me. Surely if interviewed in confidence , it can't be used against you? perhaps it can by management claiming its conspiracy. All seems very wrong to me. Will find out more details later no doubt.

Why aren't Personnel/Human Resources department involved in all this. That's their job and I haven't heard them mentioned once.
If the company carries on the way they are your daughter will soon have a case of constructive dismissal against them.

I've no idea about HR being involved. As guess work, I would imagine that the Area Manager has been liaising with HR, which is why someone external people is being involved next week.
I personally have a theory that there is a cover up for bad management of the situation and that they are scaring people into backing down.
She has been told that there is a formal complaint, but hasn't had a copy of the complaint, so doesn't yet know the details of her so called bullying.